Automated chemical analytical systems for biomedical and clinical applications have seen many changes over the past 25 to 30 years. Early equipment of this type could perform basic electrolyte, glucose and bun (urea) measurements at a rate of 60 samples per hour. Improved equipment introduced in the early 1970's allowed for analysis of up to 19 chemistries per sample at a rate of about 90 samples per hour. These systems introduced quality control monitoring and other software features that provided high quality laboratory results.
Centrifugal analyzers later introduced the concept of automated multiple chemistries that could take place in the same time/temperature environment. These later systems featured the ability to perform relatively high speed kinetic analysis on up to forty separate samples per analytical run. Centrifugal analyzers advanced the concept of single, stable reagents for several common clinical substrates and enzymes.
Originally configured as a batch analyzer, the centrifugal concept has evolved to a random access tool for analysis purposes and has been coupled to ion-specific electrodes to form the basis of a modern moderate throughput chemistry analyzer. Applications for this type of analyzer have expanded to include enzyme kinetics, enzyme immunoassays, specific protein assays, coagulation assays, and agglutination blood grouping assays. Optics capabilities have been added and expanded in these systems to include spectrophotometric, chemiluminescence, fluorescence, turbidimetric and nephelometric measurements. Sample and reagent volumes have been decreased from the more traditional 500 microliter ranges to a range of 100 to 200 microliters.
The late 1970's and early 1980's demanded a change in philosophy of automated chemical analyzers and systems designed for biomedical research. Technology and reliability are now assumed to be a given and high performance is required in such systems. The important driving forces for instrument development have become non-supervised automation, multiple analytical functions within a single analytical system, discrete operation where one to more than 20 chemistries are performed per sample, simplicity in analytical operations, internal quality checks, bidirectional interfaces to host computers, high throughput, and cost effective operation. Typical automated chemical analyzers in the moderate range (for small to medium laboratories) must now have random access operation, discrete test capabilities and the capacity for producing 1000 tests per hour. High throughput analyzers must be capable of producing from 5000 to 10,000 test results per hour.
Automated analyzers are currently facing the need to meet new technological challenges (i.e., growing numbers of immunoassays on different media and DNA/RNA probes) while also performing present methodology (i.e., substrates, enzymes, electrolytes, immunoassays for therapeutic drugs, drugs of abuse, and thyroid function) and while further experiencing regulatory and budgetary pressures requiring higher accuracy and improved cost effectiveness. Tightened regulation of the operation of such systems requires more stringent proficiency testing, which will increase the need for quality control checks, improved accuracy, and precise performance. In addition, the number of qualified medical technologists has decreased, greatly increasing the need for automated multi-function analytical systems designed to be operated by personnel of limited skills.
All current high volume chemistry analyzers are very complex, require extensive electrical and distilled water service, and occupy substantial laboratory space. They are competitive because they are fast, use small amounts of reagent, are relatively easy to use, and are operated on a random access basis. They can be adapted to provide more than 35 chemistries on-board, including immunoassays.
New automated analyzer systems now must have increased technological capabilities, but must also cost less to purchase and, as important, must cost less to operate. Finally, such systems must exhibit a unique economy of reagent consumption to be acceptable in this field.
The present system arose as a direct result of an attempt to simplify the technology used in the currently-expanding dried blood spot market that is being explored in great detail by the life insurance testing industry. This led to testing of a system that can perform multiple chemistries or immunoassays on a single spot of whole blood or serum in the same time and temperature dimension. By simultaneously performing multiple analyses, the throughput of the system can be very competitive with the most complex of the current chemistry analyzers.
The system described below evidences several distinct advantages: (1) it can be relatively small and less complex than current systems, (2) it does not require extensive plumbing and washing systems, (3) it can be part of a whole blood system using a dedicated special sampling device, (4) it can use relatively simple liquid reagents, (5) its sample and testing media permit employment of complex immunoassay systems, including DNA and RNA probes, and (6) it lends itself to positive sample identification schemes from bedside to final result.